getTap.swift

// On the view's code
func setupGestures() {
    let tap = UITapGestureRecognizer(target: self, action: #selector(callDelegateTap))
    addGestureRecognizer(tap)
}

// On the test code
func test_tappingView_shouldCallDelegate() {
    let sut = MyView()
    let gesture = sut.gestureRecognizers?.first { $0 is UITapGestureRecognizer }
    let target = (gesture?.value(forKey: "_targets") as? [NSObject])?.first
    let selectorString = String(describing: target)
        .components(separatedBy: ", ")
        .first?
        .replacingOccurrences(of: "(action=", with: "")
        .replacingOccurrences(of: "Optional(", with: "") ?? ""
    
    sut.perform(.init(stringLiteral: selectorString))
    
    XCTAssertTrue(delegateSpy.viewTappedCalled)
}